/**
 *    Copyright 2009-2018 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package com.yinsin.jpabatis.builder.annotation;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

import com.yinsin.jpabatis.builder.BuilderException;
import com.yinsin.jpabatis.builder.SqlSourceBuilder;
import com.yinsin.jpabatis.config.Configuration;
import com.yinsin.jpabatis.mapper.BoundSql;
import com.yinsin.jpabatis.mapper.SqlSource;
import com.yinsin.jpabatis.parsing.PropertyParser;
import com.yinsin.jpabatis.reflection.ParamNameResolver;

/**
 * @author Clinton Begin
 * @author Kazuki Shimizu
 */
public class ProviderSqlSource implements SqlSource {

	private final Configuration configuration;
	private final SqlSourceBuilder sqlSourceParser;
	private final Class<?> providerType;
	private Method providerMethod;
	private String[] providerMethodArgumentNames;
	private Class<?>[] providerMethodParameterTypes;
	private ProviderContext providerContext;
	private Integer providerContextIndex;

	/**
	 * @deprecated Please use the
	 *             {@link #ProviderSqlSource(Configuration, Object, Class, Method)}
	 *             instead of this.
	 */
	@Deprecated
	public ProviderSqlSource(Configuration configuration, Object provider) {
		this(configuration, provider, null, null);
	}

	/**
	 * @since 3.4.5
	 */
	public ProviderSqlSource(Configuration configuration, Object provider, Class<?> mapperType, Method mapperMethod) {
		String providerMethodName;
		try {
			this.configuration = configuration;
			this.sqlSourceParser = new SqlSourceBuilder(configuration);
			this.providerType = (Class<?>) provider.getClass().getMethod("type").invoke(provider);
			providerMethodName = (String) provider.getClass().getMethod("method").invoke(provider);

			for (Method m : this.providerType.getMethods()) {
				if (providerMethodName.equals(m.getName()) && CharSequence.class.isAssignableFrom(m.getReturnType())) {
					if (providerMethod != null) {
						throw new BuilderException("Error creating SqlSource for SqlProvider. Method '" + providerMethodName + "' is found multiple in SqlProvider '"
								+ this.providerType.getName() + "'. Sql provider method can not overload.");
					}
					this.providerMethod = m;
					this.providerMethodArgumentNames = new ParamNameResolver(configuration, m).getNames();
					this.providerMethodParameterTypes = m.getParameterTypes();
				}
			}
		} catch (BuilderException e) {
			throw e;
		} catch (Exception e) {
			throw new BuilderException("Error creating SqlSource for SqlProvider.  Cause: " + e, e);
		}
		if (this.providerMethod == null) {
			throw new BuilderException("Error creating SqlSource for SqlProvider. Method '" + providerMethodName + "' not found in SqlProvider '" + this.providerType.getName()
					+ "'.");
		}
		for (int i = 0; i < this.providerMethodParameterTypes.length; i++) {
			Class<?> parameterType = this.providerMethodParameterTypes[i];
			if (parameterType == ProviderContext.class) {
				if (this.providerContext != null) {
					throw new BuilderException("Error creating SqlSource for SqlProvider. ProviderContext found multiple in SqlProvider method (" + this.providerType.getName()
							+ "." + providerMethod.getName() + "). ProviderContext can not define multiple in SqlProvider method argument.");
				}
				this.providerContext = new ProviderContext(mapperType, mapperMethod);
				this.providerContextIndex = i;
			}
		}
	}

	@Override
	public BoundSql getBoundSql(Object parameterObject) {
		SqlSource sqlSource = createSqlSource(parameterObject);
		return sqlSource.getBoundSql(parameterObject);
	}

	private SqlSource createSqlSource(Object parameterObject) {
		try {
			int bindParameterCount = providerMethodParameterTypes.length - (providerContext == null ? 0 : 1);
			String sql;
			if (providerMethodParameterTypes.length == 0) {
				sql = invokeProviderMethod();
			} else if (bindParameterCount == 0) {
				sql = invokeProviderMethod(providerContext);
			} else if (bindParameterCount == 1
					&& (parameterObject == null || providerMethodParameterTypes[providerContextIndex == null || providerContextIndex == 1 ? 0 : 1].isAssignableFrom(parameterObject
							.getClass()))) {
				sql = invokeProviderMethod(extractProviderMethodArguments(parameterObject));
			} else if (parameterObject instanceof Map) {
				@SuppressWarnings("unchecked")
				Map<String, Object> params = (Map<String, Object>) parameterObject;
				sql = invokeProviderMethod(extractProviderMethodArguments(params, providerMethodArgumentNames));
			} else {
				throw new BuilderException("Error invoking SqlProvider method (" + providerType.getName() + "." + providerMethod.getName()
						+ "). Cannot invoke a method that holds " + (bindParameterCount == 1 ? "named argument(@Param)" : "multiple arguments")
						+ " using a specifying parameterObject. In this case, please specify a 'java.util.Map' object.");
			}
			Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
			return sqlSourceParser.parse(replacePlaceholder(sql), parameterType, new HashMap<String, Object>());
		} catch (BuilderException e) {
			throw e;
		} catch (Exception e) {
			throw new BuilderException("Error invoking SqlProvider method (" + providerType.getName() + "." + providerMethod.getName() + ").  Cause: " + e, e);
		}
	}

	private Object[] extractProviderMethodArguments(Object parameterObject) {
		if (providerContext != null) {
			Object[] args = new Object[2];
			args[providerContextIndex == 0 ? 1 : 0] = parameterObject;
			args[providerContextIndex] = providerContext;
			return args;
		} else {
			return new Object[] { parameterObject };
		}
	}

	private Object[] extractProviderMethodArguments(Map<String, Object> params, String[] argumentNames) {
		Object[] args = new Object[argumentNames.length];
		for (int i = 0; i < args.length; i++) {
			if (providerContextIndex != null && providerContextIndex == i) {
				args[i] = providerContext;
			} else {
				args[i] = params.get(argumentNames[i]);
			}
		}
		return args;
	}

	private String invokeProviderMethod(Object... args) throws Exception {
		Object targetObject = null;
		if (!Modifier.isStatic(providerMethod.getModifiers())) {
			targetObject = providerType.newInstance();
		}
		CharSequence sql = (CharSequence) providerMethod.invoke(targetObject, args);
		return sql != null ? sql.toString() : null;
	}

	private String replacePlaceholder(String sql) {
		return PropertyParser.parse(sql, configuration.getVariables());
	}

}
